A directed graph, or digraph, may include a set of nodes and a set of directed edges. The nodes may also be referred to as vertices, and the directed edges may also be referred to as arcs or arrows. Each directed edge leads from one specific node to another specific node in the graph.
Directed graphs may be used to represent various types of data. Under some circumstances, directed graphs, such as those used to represent data, may need to be stored (e.g., in persistent or non-transient memory) for some periods of time.